Sonographic appearances in transudative pleural effusions: not always an anechoic pattern.

Pleural effusion patterns in sonographic appearances can be subclassified as anechoic, complex nonseptated, complex septated and homogeneously echogenic. Previous studies have suggested that transudates are usually anechoic; however, in daily practice we find frequently that heterogeneous echogenic material is present in transudative pleural effusions. This clinical study was to re-evaluate the sonographic appearances of transudative pleural effusions.